The New South Wales (NSW) government in Australia has introduced a new technology for Sydney Trains to detect troublemakers and vandals tresspassing on rail tracks.

The new technology uses motion-activated cameras that capture still images of culprits trespassing on the railway corridor illegally or breaking into fenced-off areas of the rail network.

The images are sent to Sydney Trains security monitoring staff who then alert the police.

NSW Minister for Transport and Infrastructure Andrew Constance said: "Mirroring the success of Mousetrap technology that catches graffiti vandals on train carriages, these cameras, known as 'Mousetrap: Land Based', are about saving lives by catching rail corridor trespassers in the act."

"This can be deployed anywhere, at any time. The simple message is: don't break the law or you'll be tracked down."

By using this technology, police have already arrested a trespasser and a group of youths who were placing rocks on the line on the Central Coast.

The roving cameras can be installed in bushland along fencing and track lines to target known trespassing hot spots.

Infrared capabilities of the cameras detect illegal activity at night, including people who take shortcuts across the tracks.

Constance added: "We do as much as we can to keep train customers safe, including having more than 10,000 CCTV cameras across the network, emergency help points at stations so people can report trespassing and installing fencing around our stabling yards and parts of the corridor."

"The simple message is: don't break the law or you'll be tracked down."

In May, Sydney Trains tested a new graffiti-fighting weapon, a vapour-sensing system that automatically detects spray paint or marker pens on carriage surfaces.

Called Mousetrap device, the electronic chemical sensor was fitted on certain trains to help catch offenders red-handed.

The device detects the smell of the spray and then immediately alerts train guards.

Once the sensors of the device are triggered, an alarm is sent to Police Transport Command (PTC) and Sydney Trains control staff who can view live CCTV recordings to intercept the criminals.

So far the vapour-sensing system led to the arrest of more than 30 offenders.

In the last financial year, the government has spent A$34m to remove graffiti from the Sydney Trains